This invention relates to gear pumps, and more particularly to sealed, leak-proof gear pumps usable with non-lubricating liquids.
Some systems involve the pumping of liquids that can not be permitted to contact the environment, either by leakage into the pump or escape of liquid from the pump. Small precision gear pumps with sealed magnetically coupled drives are usable in many such systems in the chemical, dye, textile, instrumentation, food, drug, and medical fields. Magnetically coupled drives eliminate drive shaft seals, which are a major source of pump leakage and contamination of the liquid being pumped. However, magnetic drive couplings have limited torque capacity. Therefore friction within the pump chamber should be minimized so that an increased amount of such torque capacity can be used for pumping. Prior art magnetically driven gear pumps have attempted to minimize friction by using relatively soft gears made from plastic or carbon; these soft gears are enclosed in a close fitting metal or plastic housing so that wear at the gear tips is relied upon to compensate for manufacturing tolerances and gear shaft bearing wear. However, such soft gears wear out prematurely due to normal tooth loads on the soft material. This leads to leakage between the gear teeth, loss of pressure and pumping capacity, and unnecessary repair expense.
Accordingly, it is an object of this invention to provide an improved gear pump.
Another object is to provide a magnetically-driven sealed gear pump with a reduced internal friction load.
Another object is to provide a precision leak-proof, contamination-free gear pump having increased pumping out-put and pressure capacity.
Another object is to provide a gear pump in which normal wear of the gear shaft bearings does not result in appreciable loss of pressure or output.
Another object is to provide a gear pump in which soft, individually replaceable seals minimize the wear on metal gear teeth.
Another object is to provide a gear pump that is usable with non-lubricating and corrosive liquids over a wide temperature range.
Another object is to provide a sealed, precision gear pump that has a long life, is relatively inexpensive to manufacture, and does not have defects found in similar prior art gear pumps.
Other objects and advantages of the invention will be found in the specification and claims, and the scope of the invention will be set forth in the claims.